1. Field of the Invention
The present invention relates to an image forming apparatus, such as a printer, a facsimile, a copier, or the like, using electrophotographic recording technique or electrostatic recording technique.
2. Description of the Related Art
The image forming apparatus that forms an image on a recording sheet using toner is required to reliably provide fixability of the toner on the recording sheet. However, there are various factors affecting the fixability of the toner. For example, the factors may be an environmental temperature (ambient temperature) of the location where the image forming apparatus is disposed, a voltage state of a power supply, and the like.
The reliable fixability is desired to be secured by taking into account such various factors affecting the fixability.
Meanwhile, considering the usability, the image forming apparatus in recent years is desired to shorten a printout time for a first recording sheet after a print command is given (first printout time, hereinafter, referred to as FPOT). Therefore, it is desired to reliably secure the fixability regardless of the factors affecting the fixability, and to shorten the FPOT.
Japanese Patent Laid-Open No. 6-64219 discloses that FPOT is shortened by starting paper feeding when a rotation speed of a scanning motor reaches a predetermined rotation speed which is less than a rotation speed for image scanning.
Japanese Patent Laid-Open No. 8-152834 discloses that FPOT is shortened by predicting a rising-completion timing of a fixing unit or a scanning motor, and starting the paper feeding before the completion of the rising.
Japanese Patent Laid-Open No. 8-83016 discloses that warming-up control is set in accordance with environmental indices, such as a voltage state of a power supply, an environmental temperature, and the like, affecting the fixability.
A fourth embodiment in Japanese Patent Laid-Open No. 2001-290389 discloses that a paper-feeding timing is determined in accordance with room-temperature information.
However, the configurations disclosed in Japanese Patent Laid-Open Nos. 6-64219 and 8-152834 do not take into account the factors, such as the environmental temperature, affecting the fixability. Therefore, defective fixing may occur. For example, even through the fixing unit is sufficiently warm since printing is just performed, the fixability may not be secured when a recording sheet is cold due to a low-temperature environment.
The configuration disclosed in Japanese Patent Laid-Open No. 8-83016 indicates that warming-up control is set in accordance with the environmental indices, and that the paper-feeding timing may be set after the warming-up is completed in any environmental index.
The configuration disclosed in Japanese Patent Laid-Open No. 2001-290389 only takes into account the room temperature, and does not consider other factors affecting the fixability.